Abstract

Doroodzan earth dam is located in 85 km north western of Shiraz. Because of the unusual
seepage flow in the left abutment, in 1992 an impermeable vane was grouted there. Soon after
that, obvious changes in water Table profile occurred and simultaneously some incremental
number of cracks in left abutment crest was appeared. In present study seepage through left
abutment has been analyzed by considering water Table changes. Different phreatic surface
line was carried out from recent 20 years in order to find the most vulnerable one. In addition,
Seismic loading used to get proper perception of seismic stability. First, by gathering data
from piezometric head through the left abutment, most critical phreatic line in left abutment
section of dam was observed. Then by using present phreatic surface in numerical modeling
of critical section in the left abutment of dam, long term stability of downstream in different
situation were calculated. The conditions were changed by increasing the saturation zone and
the time which saturation zone stay through the downstream body.